Hollow golf club heads and manufacturing method thereof

ABSTRACT

The present invention relates to the hollow golf club heads and manufacturing method thereof

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 10/398,158, filed Sep. 19, 2001, which claims foreign priority benefits of International Patent Application No. PCT/KR2001/001574, filed Sep. 19, 2001, and Korean Patent Application No. 200064348, filed Oct. 31, 2000, all of which are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present invention relates to a hollow golf club head and the manufacturing method thereof In detail, the present invention relates to the manufacturing method of the hollow golf club head comprising: molding a golf club head body, composed of a sole, a crown, and a hosel, out of light materials; molding a face out of heavy materials; and conjugating the face with the backside of the golf club head body, and the hollow golf club head manufactured by the method.

BACKGROUND ART

In conventional manufacturing methods of the hollow golf club head, components such as a face, a sole, a crown, and a hosel were processed into a built-in type by casting or forging and were conjugated by one of the processes among fusion welding, cold welding, brazing and so forth.

Moreover, recently the conjugating process of different materials that are excellent in the strength and the firmness is popularly utilized, for the purpose of improving the strength, the firmness and the characteristic of driver distance of the golf club.

Nevertheless, because of the disagreement in the coefficient of thermal expansion of different materials, conventional method of conjugating different materials have the problem, in that the fusion welding process and the cold welding process were impossible owing to melting step of the base metal in these processes. Thereupon, the brazing process or the deformation process is commonly used in conjugating different materials.

Furthermore, such conventional conjugating methods of different materials are disadvantageous, in that the processes are complicated and the production cost is high and the goods made through the processes are inferior in the strength, the firmness and the driver distance, that the processes are not commonly used.

Accordingly, the present invention, made keeping in mind the above problems occurring in the prior art and focused on the convenience of riveting process in conjugating different materials, has an object to provide a hollow golf club head composed of a body which is molded out of light materials such as titanium, and a face which is molded out of heavy materials excellent in the strength and the firmness such as Aermet and Nitinol. Thereby, the face of the golf club head is improved in the firmness and the strength and the shot hit by the golf club head has the improved characteristics of driver distance and the direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The above object, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a process diagram of an exemplary manufacturing method of the hollow golf club head according to the present invention;

FIG. 2 is a perspective view of an exemplary hollow golf club head and the manufacturing method thereof according to the present invention;

FIG. 3 is a graph shows COR of the golf club with various materials during the last few decades; and,

FIG. 4 a-4 i are the pictures showing the steps of the method for manufacturing a hollow golf club head according to the present invention.

DISCLOSURE OF THE INVENTION

In order to accomplish the above object, the present invention provides the manufacturing method comprising: the riveting preparation step, in which the hollow golf club head body is made-up of a crown, a hosel, and a sole molded out of same material, and processed into a built-in type, and in which a face is molded out of different material; the gasket insertion step, in which the gasket is inserted between the face and the backside of the golf club head body, and the riveting conjugation step, in which the golf club head body, the face and the inserted gasket are conjugated by riveting.

Hereinafter, the present invention is described in detail with reference to exemplary illustrations, but by no means limited by the following illustrations. And present invention ranges over the slightly modified inventions compared with it.

The exemplary illustrations of the present invention are described in detail with reference to the following drawings.

FIG. 1 is a process diagram of an exemplary manufacturing method, and FIG. 2 is a perspective view of riveting conjugation process of the golf club head body and the face molded out of different material from the golf club head body, according to the exemplary illustration of the present invention.

As shown in FIG. 1 and FIG. 2, the manufacturing method of the hollow golf club head according to the present invention comprises: the riveting preparation step, in which the hollow golf club head body is made-up of a crown, a hosel, and a sole molded out of same material, and is processed into a built-in type, and a face is molded out of different material from the golf club head body; the gasket insertion step, in which the gasket is inserted between the face and the backside of the golf club head body, and the riveting conjugation step, in which the golf club head body, the face and the inserted gasket are conjugated by riveting.

According to present invention, the purpose of using the gasket is different from that of prior arts which used the gasket to isolate the face plate from the golf club head body The present invention uses the gasket to facilitate the conjugation between the face plate and the golf club head body. If the face and the head body are different in material, they cannot be directly welded because of the difference of the coefficient of thermal expansion. Therefore, to conjugate the face with the head body by riveting, firstly the face must be riveted to a member which consists of the same material with that of the head body, and then the member is conjugated with the head body by welding, etc.

Hereinafter, the manufacturing processes, of the hollow golf club head according to the present invention, are respectively described in detail.

Riveting Preparation Step (S1)

The hosel (33), the sole (32), and the crown (31) is molded out of conventionally used light materials such as titanium and they are processed into a built-in type golf club head body.

Sticking a weight, molded out of copper or tungsten, to the hosel sets the centroid of the golf club head back, and thereby the characteristic of driver distance of the golf club head can be improved.

Moreover, the face, which has the function of stroke plate as the most important part of the golf club head, is molded out of aerospace materials such as Aermet and Nitinol that has high strength and high firmness.

On the golf club head body and the face manufactured through the above processes, holes are made at the riveting portion by drilling, for the purpose of minimizing the damage on the materials, and the diameter of the drilled holes is preferably larger than the general, and during drilling the taper, having the appointed degree, is prepared for the convenience of riveting process.

Gasket Insertion Step (S2)

As shown in FIG. 2, by riveting after inserting a gasket between the backside (70) of the golf club head body and the face (40), the outbreak of a gap between the face and the backside of the golf club head body can be prevented in advance, and the effect of impact absorbing and the prevention of vibration are obtained.

The inserted gasket (40) is molded out of commonly used materials such as copper and the shape memory alloy, which are excellent in the impact resistance and the prevention of vibration.

The gasket insertion step can be omitted, if the reliable sealing effect between the face and the backside of the golf club head body can be guaranteed.

Riveting Conjugation Step (S3)

After inserting the gasket between the face (50) and the backside (70) of the golf club head body (30), the rivets (15) are pierced through the rivet hole in accordance with the axial direction and thereafter riveting process is accomplished.

The mechanical characteristics of the hollow golf club head of the present invention are described in detail with reference to Table 1.

Compared with the golf club heads manufactured through the conventional manufacturing processes such as brazing and plastic deformation, the golf club head including a face molded out of titanium has the volume of 260˜320 cc, the strength of 1.0˜1.3 Gpa, and the firmness of HRc30. Besides, the golf club head including a face molded out of the high strength alloy has the volume of 200˜250 cc, the strength of 1.5˜2.0 Gpa, and the firmness of HRc45˜55.

Grafted with the merits of the golf club heads which are made of titanium and the high strength alloy, the golf club head according to the present invention has the volume of 260˜320 cc, the strength of 1.5˜2.0Gpa, and the firmness of HRc45˜55.

Moreover, in an aspect of the driver distance ratio, if the golf club head including the face molded out of titanium has the ratio of 100%, the golf club head including the face molded out of the high strength alloy has the ratio of 120%.

The golf club head processed through the manufacturing processes of the present invention provides the driver distance ratio of 120%. Conventional products The high Products of the Division Titanium alloy strength alloy present invention Volume 260˜320 200˜250 260˜300 Driver distance 100 120˜130 120˜130 ratio Strength of face 1.0˜1.3 1.5˜2.0 1.5˜2.0 Firmness of face  30 45˜55 45˜55 [note] The above numerical values are the arithmetic mean of mechanical characteristic values estimated from ten products.

Because the purpose of the gasket of the present invention is different from that of prior arts, the sequence of riveting and conjugating is quite important in the present invention. In the present invention, the conjugating must be done after the riveting, because the face must be riveted to the gasket before the gasket is conjugated(welded) with the head body.

But according to prior arts, the sequence is not important. The face can be conjugated with the gasket regardless that the gasket is conjugated with the head body. And the face can be conjugated with head body and the gasket is inserted between the face and the head body.

However, in the present invention, if the gasket is conjugated with the head body before the face is riveted to the gasket, the golf club cannot be manufactured.

According to prior arts, either screws or rivets can be used to join a face plate to a golf club head body. But the joining method between screws and rivets are quite different. Screws can be entered into only one side (e.g. front side of face), but rivets must be handled on both sides (e.g. front and rear sides of the face). Mechanically, it is obvious that the joining strength of rivet is much more than that of screw. So if a face plate can be riveted to head body instead of by screwing, the face plate and head body better behavior as one body and the face plate better function mechanically

The effect of high COR (coefficient of restitution) of the present invention is derived not by isolating the striking plate from the golf club head body, but by manufacturing the face with the material of Aermet etc riveted to the head body.

The COR of the hollow golf club head manufactured under the method of the present invention is highly improved. The effect of the improvement of COR according to the present invention is as follows.

One of the most important things in the golf game is driver distance. The mission of the driver is the flying distance of a ball. One of the most widely used means in measuring the driver distance is the (COR: Coefficient Of Restitution). In other words, the COR is spring-like effect, the higher the COR is, the farther a ball flies. So, all golf-makers are doing their best in increasing the COR of the golf club. But the COR only increases when the material and the conjugation technology are changed. FIG. 3 shows COR of the golf club with various materials during the last few decades. According to FIG. 3, it takes more than 10 years in increasing the COR 0.03-0.04.

The golf clubs manufactured by the method of the present invention are tested by the KIMM (Korea Institute of Machinery and Materials), and the average of COR from 5 tests is 0.90 as shown in the following test result. Test specimen COR(e) First Generation #103 1st time 0.89 2nd time 0.90 3rd time 0.90 4th time 0.91 5th time 0.89 Average 0.90 * Test method: Pendulum type impact test. * Reference: “On Low-Velocity Impact Testing of Composite Materials”, Peter O. Sjoblom, J. Timothy Hartness, Tobey M. Cordell, Journal of Composite Materials, Vol. 22-January 1988.

The golf club manufactured by the method of the present invention are tested by the KIMM (Korea Institute of Machinery and Materials) in comparing with the golf clubs made by Taylormade™ and Callaway™. The “C” represents the Callaway, the “H” represents the present invention, and the “T” represents the Taylormade™ in the following test result. Test Specimen COR(e) C 0.86 H 0.90 T 0.85 * Test specimen: 3 type(C, H, T label) * Test Method: Pendulum type impact test * Reference: “On Low-Velocity Impact Testing of Composite Materials”, Peter O. Sjoblom, J. Timothy Hartness, Tobey M. Cordell, Journal of Composite Materials, Vol. 22-January 1988. * The COR is the average value from 5 times of tests

The steps of the method for manufacturing a hollow golf club head according to the present invention are shown in FIG. 4 a-4 i. FIG. 4 a shows the gasket out of titanium, FIG. 4 b shows the drilling holes on the gasket, FIG. 4 c shows the drilling holes on the face out of Aermet, FIG. 4 d shows the gasket and the face, FIG. 4 e shows the riveting face to the gasket, FIG. 4 f the front side of the face-gasket after riveting, FIG. 4 g shows the back side of the face-gasket after riveting, FIG. 4 h shows the conjugation of gasket with head body, FIG. 4 i shows the abrading and painting of the golf club head.

INDUSTRIAL APPLICABILITY

As described above, the riveting process of conjugating different materials of the present invention makes the manufacturing processes convenient and lowers the manufacturing cost, and thereby it enables mass production of the hollow golf club heads. Since the body is molded out of commonly used light materials such as titanium alloy and the face out of particularly strong and firm materials such as Aermet and Nitinol, the hollow golf club head of the present invention has a large volume and improved in the strength and the firmness. Moreover, the driver distance and the accuracy in direction are improved. The hollow golf club head of the present invention is thus highly applicable in the golf club heads manufacturing industrial field. 

1. A method for manufacturing a hollow golf club head comprising preparing a golf club head body and a gasket molded out of light materials of titanium, and a face out of particularly strong materials chosen from Aermet and Nitinol; drilling holes at the riveting portion on said gasket and said face; riveting said face to the backside of said gasket; and, conjugating said gasket with said golf club head body.
 2. A hollow golf club head manufactured by the method according to claim
 1. 